It is expected that the concept of paying by time watched rather than paying for an entire movie will be a viable business model for distributing multimedia content over the Internet. The concept may not be suitable for movies which have a well defined start time and duration and for which the majority of viewers want to watch the entire movie or nothing. However, content such as ongoing world news, fashion shows, general entertainment with music, skits, dance, etc., would benefit from options to sell only a part of such content based on actual time spent watching.
Most known techniques do not scale well to the number of users expected to be serviced on the Internet. Most published algorithms are suitable for specific constraint domains, such as video teleconferencing, which usually have a relatively small number of participants. Other algorithms do not scale well because of a high requirement on the number of messages sent when a participant leaves the group, or a large number of keys stored by each participant. None of these techniques are suitable for a broadcast-like distribution of video over the Internet.
In prior techniques, when a member of a multicast group wanted to leave the group, the rest or a large portion of the group might have to be given a new set of security keys to ensure security. This is an expensive and time consuming operation, especially when the group is very large (e.g., millions of viewers).